Encryption for a distributed filesystem

ABSTRACT

A computing device comprising a frontend and a backend is operably coupled to a plurality of storage devices. The backend comprises a plurality of buckets. Each bucket is operable to build a failure-protected stripe that spans two or more of the plurality of the storage devices. The frontend is operable to encrypt data as it enters the plurality of storage devices and decrypt data as it leaves the plurality of storage devices.

PRIORITY CLAIM

This application claims priority to the following application, which ishereby incorporated herein by reference:

U.S. provisional patent application 62/682,198 titled “ENCRYPTION FOR ADISTRIBUTED FILESYSTEM” filed on Jun. 8, 2018.

BACKGROUND

Limitations and disadvantages of conventional approaches to data storagewill become apparent to one of skill in the art, through comparison ofsuch approaches with some aspects of the present method and system setforth in the remainder of this disclosure with reference to thedrawings.

INCORPORATION BY REFERENCE

U.S. patent application Ser. No. 15/243,519 titled “Distributed ErasureCoded Virtual Filesystem” is hereby incorporated herein by reference inits entirety.

BRIEF SUMMARY

Methods and systems are provided for encryption in a distributedfilesystem substantially as illustrated by and/or described inconnection with at least one of the figures, as set forth morecompletely in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates various example configurations of a distributedfilesystem in accordance with aspects of this disclosure.

FIG. 2 illustrates an example configuration of a distributed filesystemnode in accordance with aspects of this disclosure.

FIG. 3 illustrates another representation of a distributed filesystem inaccordance with an example implementation of this disclosure.

FIG. 4 illustrates an example of a computing device in an encryptedfilesystem in accordance with one or more embodiments of the presentdisclosure.

FIG. 5 illustrates an example of a cluster of computing devices inaccordance with one or more embodiments of the present disclosure.

FIG. 6 is a flowchart illustrating an example method for reading from aclient in an encrypted filesystem.

FIG. 7 is a flowchart illustrating an example method for writing to aclient in an encrypted filesystem.

DETAILED DESCRIPTION

Traditionally, filesystems use a centralized control over the metadatastructure (e.g., directories, files, attributes, file contents). If alocal filesystem is accessible from a single server and that serverfails, the filesystem's data may be lost if as there is no furtherprotection. To add protection, some filesystems (e.g., as provided byNetApp) have used one or more pairs of controllers in an active-passivemanner to replicate the metadata across two or more computers. Othersolutions have used multiple metadata servers in a clustered way (e.g.,as provided by IBM GPFS, Dell EMC Isilon, Lustre, etc.). However,because the number of metadata servers in a traditional clustered systemis limited to small numbers, such systems are unable to scale.

The systems in this disclosure are applicable to small clusters and canalso scale to many, many thousands of nodes. An example embodiment isdiscussed regarding non-volatile memory (NVM), for example, flash memorythat comes in the form of a solid-state drive (SSD). The NVM may bedivided into 4 kB blocks and 128 MB chunks. Extents may be stored involatile memory, e.g., RAM for fast access, backed up by NVM storage aswell. An extent may store pointers for blocks, e.g., 256 pointers to 1MB of data stored in blocks. In other embodiments, larger or smallermemory divisions may also be used. Metadata functionality in thisdisclosure may be effectively spread across many servers. For example,in cases of “hot spots” where a large load is targeted at a specificportion of the filesystem's namespace, this load can be distributedacross a plurality of nodes.

FIG. 1 illustrates various example configurations of a distributedfilesystem in accordance with aspects of this disclosure. Shown in FIG.1 is a local area network (LAN) 102 comprising one or more nodes 120(indexed by integers from 1 to J, for j≥1), and optionally comprising(indicated by dashed lines): one or more dedicated storage nodes 106(indexed by integers from 1 to M, for M≥1), one or more compute nodes104 (indexed by integers from 1 to N, for N≥1), and/or an edge routerthat connects the LAN 102 to a remote network 118. The remote network118 optionally comprises one or more storage services 114 (indexed byintegers from 1 to K, for K≥1), and/or one or more dedicated storagenodes 115 (indexed by integers from 1 to L, for L≥1).

Each node 120 _(j) (j an integer, where 1≤j≤1) is a networked computingdevice (e.g., a server, personal computer, or the like) that comprisescircuitry for running processes (e.g., client processes) either directlyon an operating system of the device 104 n and/or in one or more virtualmachines running in the device 104 _(n).

The compute nodes 104 are networked devices that may run a virtualfrontend without a virtual backend. A compute node 104 may run a virtualfrontend by taking a single root input/output virtualization (SR-IOV)into the network interface card (NIC) and consuming a complete processorcore. Alternatively, the compute node 104 may run the virtual frontendby routing the networking through a Linux kernel networking stack andusing kernel process scheduling, thus not having the requirement of afull core. This is useful if a user does not want to allocate a completecore for the filesystem or if the networking hardware is incompatiblewith the filesystem requirements.

FIG. 2 illustrates an example configuration of a node in accordance withaspects of this disclosure. A node comprises a frontend 202 and driver208, a memory controller 204, a backend 206, and an SSD agent 214. Thefrontend 202 may be a virtual frontend; the memory controller 204 may bea virtual memory controller; the backend 206 may be a virtual backend;and the driver 208 may be a virtual drivers. As used in this disclosure,a virtual filesystem (VFS) process is a process that implements one ormore of: the frontend 202, the memory controller 204, the backend 206,and the SSD agent 214. Thus, in an example implementation, resources(e.g., processing and memory resources) of the node may be shared amongclient processes and VFS processes. The processes of the VFS may beconfigured to demand relatively small amounts of the resources tominimize the impact on the performance of the client applications. Thefrontend 202, the memory controller 204, and/or the backend 206 and/orthe SSD agent 214 may run on a processor of the host 201 or on aprocessor of the network adaptor 218. For a multi-core processor,different VFS process may run on different cores, and may run adifferent subset of the services. From the perspective of the clientprocess(es) 212, the interface with the virtual filesystem isindependent of the particular physical machine(s) on which the VFSprocess(es) are running. Client processes only require driver 208 andfrontend 202 to be present in order to serve them.

The node may be implemented as a single tenant server (e.g., bare-metal)running directly on an operating system or as a virtual machine (VM)and/or container (e.g., a Linux container (LXC)) within a bare-metalserver. The VFS may run within an LXC container as a VM environment.Thus, inside the VM, the only thing that may run is the LXC containercomprising the VFS. In a classic bare-metal environment, there areuser-space applications and the VFS runs in an LXC container. If theserver is running other containerized applications, the VFS may runinside an LXC container that is outside the management scope of thecontainer deployment environment (e.g. Docker).

The node may be serviced by an operating system and/or a virtual machinemonitor (VMM) (e.g., a hypervisor). The VMM may be used to create andrun the node on a host 201. Multiple cores may reside inside the singleLXC container running the VFS, and the VFS may run on a single host 201using a single Linux kernel. Therefore, a single host 201 may comprisemultiple frontends 202, multiple memory controllers 204, multiplebackends 206, and/or one or more drivers 208. A driver 208 may run inkernel space outside the scope of the LXC container.

A SR-IOV PCIe virtual function may be used to run the networking stack210 in user space 222. SR-IOV allows the isolation of PCI Express, suchthat a single physical PCI Express can be shared on a virtualenvironment and different virtual functions may be offered to differentvirtual components on a single physical server machine. The I/O stack210 enables the VFS node to bypasses the standard TCP/IP stack 220 andcommunicate directly with the network adapter 218. A Portable OperatingSystem Interface for uniX (POSIX) VFS functionality may be providedthrough lockless queues to the VFS driver 208. SR-IOV or full PCIephysical function address may also be used to run non-volatile memoryexpress (NVMe) driver 214 in user space 222, thus bypassing the Linux IOstack completely. NVMe may be used to access non-volatile storage media216 attached via a PCI Express (PCIe) bus. The non-volatile storagemedia 220 may be, for example, flash memory that comes in the form of asolid-state drive (SSD) or Storage Class Memory (SCM) that may come inthe form of an SSD or a memory module (DIMM). Other example may includestorage class memory technologies such as 3D-XPoint.

The SSD may be implemented as a networked device by coupling thephysical SSD 216 with the SSD agent 214 and networking 210.Alternatively, the SSD may be implemented as a network-attached NVMe SSD222 or 224 by using a network protocol such as NVMe-oF (NVMe overFabrics). NVMe-oF may allow access to the NVMe device using redundantnetwork links, thereby providing a higher level or resiliency. Networkadapters 226, 228, 230 and 232 may comprise hardware acceleration forconnection to the NVMe SSD 222 and 224 to transform them into networkedNVMe-oF devices without the use of a server. The NVMe SSDs 222 and 224may each comprise two physical ports, and all the data may be accessedthrough either of these ports.

Each client process/application 212 may run directly on an operatingsystem or may run in a virtual machine and/or container serviced by theoperating system and/or hypervisor. A client process 212 may read datafrom storage and/or write data to storage in the course of performingits primary function. The primary function of a client process 212,however, is not storage-related (i.e., the process is only concernedthat its data is reliably stored and is retrievable when needed, and notconcerned with where, when, or how the data is stored). Exampleapplications which give rise to such processes include: email servers,web servers, office productivity applications, customer relationshipmanagement (CRM), animated video rendering, genomics calculation, chipdesign, software builds, and enterprise resource planning (ERP).

A client application 212 may make a system call to the kernel 224 whichcommunicates with the VFS driver 208. The VFS driver 208 puts acorresponding request on a queue of the VFS frontend 202. If several VFSfrontends exist, the driver may load balance accesses to the differentfrontends, making sure a single file/directory is always accessed viathe same frontend. This may be done by sharding the frontend based onthe ID of the file or directory. The VFS frontend 202 provides aninterface for routing filesystem requests to an appropriate VFS backendbased on the bucket that is responsible for that operation. Theappropriate VFS backend may be on the same host or it may be on anotherhost.

A VFS backend 206 hosts several buckets, each one of them services thefilesystem requests that it receives and carries out tasks to otherwisemanage the virtual filesystem (e.g., load balancing, journaling,maintaining metadata, caching, moving of data between tiers, removingstale data, correcting corrupted data, etc.)

A VFS SSD agent 214 handles interactions with a respective storagedevice 216. This may include, for example, translating addresses, andgenerating the commands that are issued to the storage device (e.g., ona SATA, SAS, PCIe, or other suitable bus). Thus, the VFS SSD agent 214operates as an intermediary between a storage device 216 and the VFSbackend 206 of the virtual filesystem. The SSD agent 214 could alsocommunicate with a standard network storage device supporting a standardprotocol such as NVMe-oF (NVMe over Fabrics).

FIG. 3 illustrates another representation of a distributed filesystem inaccordance with an example implementation of this disclosure. In FIG. 3,the element 302 represents memory resources (e.g., DRAM and/or othershort-term memory) and processing (e.g., x86 processor(s), ARMprocessor(s), NICs, ASICs, FPGAs, and/or the like) resources of variousnode(s) (compute, storage, and/or VFS) on which resides a virtualfilesystem, such as described regarding FIG. 2 above. The element 308represents the one or more physical storage devices 216 which providethe long term storage of the virtual filesystem.

As shown in FIG. 3, the physical storage is organized into a pluralityof distributed failure resilient address spaces (DFRASs) 518. Each ofwhich comprises a plurality of chunks 310, which in turn comprises aplurality of blocks 312. The organization of blocks 312 into chunks 310is only a convenience in some implementations and may not be done in allimplementations. Each block 312 stores committed data 316 (which maytake on various states, discussed below) and/or metadata 314 thatdescribes or references committed data 316.

The organization of the storage 308 into a plurality of DFRASs enableshigh performance parallel commits from many—perhaps all—of the nodes ofthe virtual filesystem (e.g., all nodes 104 ₁-104 _(N), 106 ₁-106 _(M),and 120 ₁-120 _(J) of FIG. 1 may perform concurrent commits inparallel). In an example implementation, each of the nodes of thevirtual filesystem may own a respective one or more of the plurality ofDFRAS and have exclusive read/commit access to the DFRASs that it owns.

Each bucket owns a DFRAS, and thus does not need to coordinate with anyother node when writing to it. Each bucket may build stripes across manydifferent chunks on many different SSDs, thus each bucket with its DFRAScan choose what “chunk stripe” to write to currently based on manyparameters, and there is no coordination required in order to do so oncethe chunks are allocated to that bucket. All buckets can effectivelywrite to all SSDs without any need to coordinate.

Each DFRAS being owned and accessible by only its owner bucket that runson a specific node allows each of the nodes of the VFS to control aportion of the storage 308 without having to coordinate with any othernodes (except during [re]assignment of the buckets holding the DFRASsduring initialization or after a node failure, for example, which may beperformed asynchronously to actual reads/commits to storage 308). Thus,in such an implementation, each node may read/commit to its buckets'DFRASs independently of what the other nodes are doing, with norequirement to reach any consensus when reading and committing tostorage 308. Furthermore, in the event of a failure of a particularnode, the fact the particular node owns a plurality of buckets permitsmore intelligent and efficient redistribution of its workload to othernodes (rather the whole workload having to be assigned to a single node,which may create a “hot spot”). In this regard, in some implementationsthe number of buckets may be large relative to the number of nodes inthe system such that any one bucket may be a relatively small load toplace on another node. This permits fine grained redistribution of theload of a failed node according to the capabilities and capacity of theother nodes (e.g., nodes with more capabilities and capacity may begiven a higher percentage of the failed nodes buckets).

To permit such operation, metadata may be maintained that maps eachbucket to its current owning node such that reads and commits to storage308 can be redirected to the appropriate node.

Load distribution is possible because the entire filesystem metadataspace (e.g., directory, file attributes, content range in the file,etc.) can be broken (e.g., chopped or sharded) into small, uniformpieces (e.g., “shards”). For example, a large system with 30 k serverscould chop the metadata space into 128 k or 256 k shards.

Each such metadata shard may be maintained in a “bucket.” Each VFS nodemay have responsibility over several buckets. When a bucket is servingmetadata shards on a given backend, the bucket is considered “active” orthe “leader” of that bucket. Typically, there are many more buckets thanVFS nodes. For example, a small system with 6 nodes could have 120buckets, and a larger system with 1,000 nodes could have 8 k buckets.

Each bucket may be active on a small set of nodes, typically 5 nodesthat that form a penta-group for that bucket. The cluster configurationkeeps all participating nodes up-to-date regarding the penta-groupassignment for each bucket.

Each penta-group monitors itself. For example, if the cluster has 10 kservers, and each server has 6 buckets, each server will only need totalk with 30 different servers to maintain the status of its buckets (6buckets will have 6 penta-groups, so 6*5=30). This is a much smallernumber than if a centralized entity had to monitor all nodes and keep acluster-wide state. The use of penta-groups allows performance to scalewith bigger clusters, as nodes do not perform more work when the clustersize increases. This could pose a disadvantage that in a “dumb” mode asmall cluster could actually generate more communication than there arephysical nodes, but this disadvantage is overcome by sending just asingle heartbeat between two servers with all the buckets they share (asthe cluster grows this will change to just one bucket, but if you have asmall 5 server cluster then it will just include all the buckets in allmessages and each server will just talk with the other 4). Thepenta-groups may decide (i.e., reach consensus) using an algorithm thatresembles the Raft consensus algorithm.

Each bucket may have a group of compute nodes that can run it. Forexample, five VFS nodes can run one bucket. However, only one of thenodes in the group is the controller/leader at any given moment.Further, no two buckets share the same group, for large enough clusters.If there are only 5 or 6 nodes in the cluster, most buckets may sharebackends. In a reasonably large cluster there many distinct node groups.For example, with 26 nodes, there are more than 64,000

$\left( \frac{26!}{{5!}*{\left( {26 - 5} \right)!}} \right)$possible five-node groups (i.e., penta-groups).

All nodes in a group know and agree (i.e., reach consensus) on whichnode is the actual active controller (i.e., leader) of that bucket. Anode accessing the bucket may remember (“cache”) the last node that wasthe leader for that bucket out of the (e.g., five) members of a group.If it accesses the bucket leader, the bucket leader performs therequested operation. If it accesses a node that is not the currentleader, that node indicates the leader to “redirect” the access. Ifthere is a timeout accessing the cached leader node, the contacting nodemay try a different node of the same penta-group. All the nodes in thecluster share common “configuration” of the cluster, which allows thenodes to know which server may run each bucket.

Each bucket may have a load/usage value that indicates how heavily thebucket is being used by applications running on the filesystem. Forexample, a server node with 11 lightly used buckets may receive anotherbucket of metadata to run before a server with 9 heavily used buckets,even though there will be an imbalance in the number of buckets used.Load value may be determined according to average response latencies,number of concurrently run operations, memory consumed or other metrics.

Redistribution may also occur even when a VFS node does not fail. If thesystem identifies that one node is busier than the others based on thetracked load metrics, the system can move (i.e., “fail over”) one of itsbuckets to another server that is less busy. However, before actuallyrelocating a bucket to a different host, load balancing may be achievedby diverting writes and reads. Since each write may end up on adifferent group of nodes, decided by the DFRAS, a node with a higherload may not be selected to be in a stripe to which data is beingwritten. The system may also opt to not serve reads from a highly loadednode. For example, a “degraded mode read” may be performed, wherein ablock in the highly loaded node is reconstructed from the other blocksof the same stripe. A degraded mode read is a read that is performed viathe rest of the nodes in the same stripe, and the data is reconstructedvia the failure protection. A degraded mode read may be performed whenthe read latency is too high, as the initiator of the read may assumethat that node is down. If the load is high enough to create higher readlatencies, the cluster may revert to reading that data from the othernodes and reconstructing the needed data using the degraded mode read.

Each bucket manages its own distributed erasure coding instance (i.e.,DFRAS 518) and does not need to cooperate with other buckets to performread or write operations. There are potentially thousands of concurrent,distributed erasure coding instances working concurrently, each for thedifferent bucket. This is an integral part of scaling performance, as iteffectively allows any large filesystem to be divided into independentpieces that do not need to be coordinated, thus providing highperformance regardless of the scale.

Each bucket handles all the filesystems operations that fall into itsshard. For example, the directory structure, file attributes and filedata ranges will fall into a particular bucket's jurisdiction.

An operation done from any frontend starts by finding out what bucketowns that operation. Then the backend leader, and the node, for thatbucket is determined. This determination may be performed by trying thelast-known leader. If the last-known leader is not the current leader,that node may know which node is the current leader. If the last-knownleader is not part of the bucket's penta-group anymore, that backendwill let the front end know that it should go back to the configurationto find a member of the bucket's penta-group. The distribution ofoperations allows complex operations to be handled by a plurality ofservers, rather than by a single computer in a standard system.

If the cluster of size is small (e.g., 5) and penta-groups are used,there will be buckets that share the same group. As the cluster sizegrows, buckets are redistributed such that no two groups are identical.

Encrypted storage is important to many different applications. Forexample, finance application must be secured according to the FederalInformation Processing Standard (FIPS), and healthcare applications mustbe secured according to the Health Insurance Portability andAccountability Act (HIPPA).

Encryption may be required for stored data. For example, if one or morestorage devices are compromised, encryption of the stored data preventsthe recovery of clear text data.

Encryption may also be required “on-the-fly” for data that istransmitted over a network. For example, encryption on the “on-the-fly”prevents eavesdropping and a man-in-the-middle trying to meddle with thedata.

FIG. 4 illustrates an example of a computing device 401 in an encryptedfilesystem 400. The computing device comprising a frontend 403 and abackend 405. The frontend 403 may encrypt and decrypt data on the clientside as it enters and leaves the system. The frontend 403 is operable toencrypt data as it is written to a data file in the system 400. Thefrontend 403 is also operable to decrypt data as it is read from a datafile in the system 400.

The frontend 403 encrypts the data at least according to a file key 413.This file key 413 may be rotated by copying the data file. The file key413 (e.g., one key per file) may be provided to a client for frontendencryption and decryption. This file key 413 may be generated by thefilesystem 401 with a FIPS-approved secure random number generator. Ifthe file key 413 is to be saved, the file key 415 may be encrypted by afilesystem key 415. Additionally, the filesystem id and the inode id maybe used as authenticated data for the file key 413. File keys can berotated by copying the file. When the file is copied, the contents willbe re-encrypted with a newly generated file key.

The filesystem key 415 (e.g., one key per each filesystem) should neverleave the filesystem's boundaries. The filesystem key 415 may begenerated by a key management system/server (KMS). If the filesystem key415 is to be saved, the filesystem key may be encrypted by a cluster key417. Additionally, the cluster id and the filesystem id may be used asauthenticated data for the filesystem key 415. The filesystem key 415may be rotated instantly by the filesystem 400. For example, thefilesystem 400 may request that the KMS generates a new key for aspecified filesystem. Newly created files will have their file key 413encrypted with the latest filesystem key 415, and updated files may havetheir file key 413 re-encrypted with the latest filesystem key 415.

The file key 413 may be encrypted by a filesystem key 415. Furthermore,the filesystem key 415 may be encrypted by a cluster key 417. The filekey 413 may be re-encrypted when the filesystem key 415 is rotated, andthe filesystem key 415 may be re-encrypted when the cluster key 417 isrotated.

The backend comprises a plurality of buckets 407 a, 407 b . . . 407 m.The computing device 401 is operably coupled to a plurality of storagedevices 409 a, 409 b, 409 c, 409 d . . . 407 n, e.g. SSD's. The numberof buckets may the less than, greater than or equal to the number ofstorage devices.

Each bucket 407 x of the plurality of buckets 407 a, 407 b . . . 407 mis operable build a failure-protected stripe 411 x that comprises aplurality of storage blocks (e.g., block x1, block x2 and block x3). Theplurality of storage blocks comprises encrypted data as well as errordetection and/or error correction coding. For illustration, stripe 411 acomprises block a1, block a2 and block a3; stripe 411 b comprises block131, block b2 and block b3; and stripe 411 c comprises block c1, blockc2 and block c3. The number of blocks in a stripe may be less than,greater than or equal to three. Each storage block of a particularstripe is located in a different storage device of the plurality ofstorage devices. All failure-protected stripes 411 built by theplurality of buckets 407 in the backend 405 are in a common filesystem400 associated with the filesystem key 415.

FIG. 5 illustrates an example of a cluster 501 of computing devices 401a, 401 b, 401 c . . . 401 p. The cluster 501 of computing devices isassociated with the cluster key 417. The cluster key 417 (e.g., one keyper each cluster) should never leave the cluster's boundaries. Thecluster key 417 may be generated by a KMS. The cluster key can berotated instantly by the KMS. Upon rotation, the KMS re-encrypts eachfilesystem key 415, and the old cluster key can be destroyed. Afilesystem does not need to be aware of the rotation. When a client(e.g., computing device 401 b or 401 c) joins the cluster 501, itregisters a public key 503 with the leader. Each client node generates along-term public/private key pair 503 on startup.

Network-encryption keys may be negotiated by two nodes (e.g., computingdevice 401 b or 401 c) for encrypting communication between those twonodes. Network interactions between nodes, including system nodes andclient nodes, are called remote procedure calls (RPCs). RPCs can marktheir arguments, output parameters and return value as encrypted. RPCsmay encrypt their argument payloads using a pre-negotiated key knownonly to the two RPC endpoints (e.g., nodes). On-demand, each client maynegotiate a session key 507 with each system node it connects to.Session keys may be negotiated with perfect forward security usingephemeral key pairs (using. e.g., ephemeral key pair generator 505)signed with the long-term key pairs (e.g., long-term key 503 b and 503c) that are generated by each node (e.g., computing device 401 b or 401c) when it was added to the cluster 501.

System-to-system keys may be used to reduce the time until anewly-started server can connect to other servers. Upon joining, thenewly-started server may receive a key from the filesystem leader. Thissystem-to-system key is encrypted and saved in a configuration. RPCsfrom servers to ServerA may use a configuration denoted as, for example,“config.serverkeys [A].”

To authenticate a client, an administrator may generate a token orcertificate that can be used by clients to join the cluster. The tokenmay be time-limited and configurable, by an administrator, based on achallenge-response mechanism. The token may identify a specific machine(e.g., my IP address or instance ID). The token may identify a clientclass, thereby allowing many machines to join using the same token. Thetoken may also be revoked by the administrator. When a token is revoked,new clients will not be able to join using the token, and an existingclient that joined using the token will be disconnected unless theexisting client has an updated and valid token.

To authorize mounts, an administrator can configure which clients(either specific machines or groups of machines) may mount whichfilesystems. This authorization is verified when a client attempts tomount the filesystem. A client that has not mounted the filesystem maybe prevented from accessing the filesystem. The administrator mayspecify whether the allowed access is read only, write only orread/write. The administrator may also allow a client to mount as root(e.g., rootsquash or no rootsquash).

Each filesystem may have a filename-encryption key that may be derivedfrom the filesystem key. When a client mounts a filesystem, the clientmay receive a filename-encryption key. The client may create files withencrypted filenames using symmetric encryption.

File data in object storage (e.g., tiered data for backups and restores)may be encrypted the same way as on-disk data. When uploading to theobject storage, the file data may contain filesystem parameters such asthe encrypted filesystem key. For example, the filesystem key may beencrypted with a special “backup-specific cluster key” that is availablevia a KMS.

If a cluster is discarded and a new cluster is created by downloading afilesystem from the object store, the downloaded filesystem may bedecrypted by the filesystem key with the backup-specific key andre-encrypted with the cluster's new cluster key.

When stowing a snapshot to a simple storage service (S3) the filesystemkeys may be re-encrypted using a new cluster key. The “stow” command maycontain the new cluster key ID and credentials to access it from theKMS. The existing filesystem keys may be re-encrypted with the newcluster key and saved in the S3 with the rest of the filesystemmetadata. Restoring a stowed snapshot requires accessing the samecluster-key specified when stowing.

System page cache may be encrypted to reduce the possibility that memory(e.g., kernel memory) will be accessed by another process. To combatthis unauthorized access, encrypted data received by a kernel page cachemay not be decrypted immediately once it is received in the network.Because the kernel will store encrypted data, a rogue application wouldbe unable to access to it. When the process that actually own the filesaccesses the encrypted data, the kernel driver, with the help of thefrontend, will decrypt the data while copying it to the memory space ofthat process. System memory will, therefore, be encrypted until it isaccessed legitimately.

The encryption and decryption processes may leverage hardwareacceleration. When performing the encryption, the filesystem may lookfor hardware that is capable of accelerating the encryption process. Thefilesystem may rank which hardware is more efficient (e.g., standard CPUopcodes, acceleration within the CPU, encryption co-processor on the, ora network card) and use the most efficient way of encrypting thedecrypting the data.

Self-encrypting drives (SED) may be used in addition to theaforementioned encryption. On top of the standard encryption code in thefilesystem, an SED may encrypt the already encrypted data that is beingreceived.

Encryption at of stored data may use symmetric encryption keys, wherethe same key is used for encrypting and decrypting the data. Based onthe filesystem configuration, there are several options for keymanagement.

The same key may be used for all the drives (e.g., SSD's). If that keyis compromised, however, all of the drives can be read.

A different key may be used for each SSD. These keys may be managed bythe filesystem randomly picking and storing the different encryptionkeys for each SSD. Alternatively, these keys may be managed by aclient's own key management system that handles creating and storingencryption keys. The filesystem may authenticate these key with theclient's KSM and request the right key for each SSD. Until the nextreboot the SSD holds the key and can use it.

Another options for key management is to have a different key for eachchunk on the SSD. This allows the support of several customers on thesame filesystem. Filesystems with different distributed failureresilient address spaces may access the same SSD agents. Each filesystemmay set a different key for each DFRAS. The SSD may not exchange a basickey on boot. Rather, different keys may be registered with the SSD onboot. If the drive requires the encryption key to be given for each IO,each key may have an index that is used by each IO. When the DFRASaccesses the SSD, the DFRAS may remember the index of its encryption keyfor its SSD and transfer it with the IO request. The filesystem may,therefore, share several workloads and different DFRAS running over thesame SSD, without compromising security.

HIPPA requires three independent copies of the data and at-restencryption. Three independent copies may be achieved by using a compoundobject storage backend that writes to two independent object storages.Data that is sent to the object storage may first be encrypted. Thefilesystem may be configured to take a snapshot and transfer thesnapshot to object storage at predefined times defined by theapplication (e.g., every 30 minutes). The cluster may have at-restencryption by integrating self-encrypting SSD drives with the KSM.

FIG. 6 is a flowchart illustrating an example method for reading from aclient in an encrypted filesystem. In block 601, a client opens a filefor read access. In block 603, after verifying the client can accessthis filesystem, the system securely sends the file key to the client'scomputing device. In block 605, the client frontend uses the file key todecrypt data read from the file.

In block 607, a session key is negotiated using an ephemeral key pairsigned with long-term keys from the client's computing device andanother computing device. In block 609, the data is encrypted using thesession key. In block 611, the data (encrypted by the session key) istransferred from the client's computing device to the other computingdevice.

In block 613, the file is closed. In block 615, the file key and sessionkey are purged from memory.

FIG. 7 is a flowchart illustrating an example method for writing to aclient in an encrypted filesystem. In block 701, a session key isnegotiated using an ephemeral key pair signed with long-term keys from aclient's computing device and another computing device. In block 703,the data is encrypted using the session key. In block 705, the data(encrypted by the session key) is transferred from the other computingdevice to the client's computing device.

In block 707, a client opens a file for write access. In block 709,after verifying the client can access this filesystem, the systemsecurely sends the file key to the client's computing device. In block711, the client frontend uses the session key to decrypt the receiveddata.

In block 713, the client frontend uses the file key to encrypt thedecrypted data. In block 715, the data (encrypted by the file key) iswritten to the open file on the client's computing device.

In block 717, the file is closed. In block 719, the file key and sessionkey are purged from memory.

While the present method and/or system has been described with referenceto certain implementations, it will be understood by those skilled inthe art that various changes may be made and equivalents may besubstituted without departing from the scope of the present methodand/or system. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the presentdisclosure without departing from its scope. Therefore, it is intendedthat the present method and/or system not be limited to the particularimplementations disclosed, but that the present method and/or systemwill include all implementations falling within the scope of theappended claims.

As utilized herein the terms “circuits” and “circuitry” refer tophysical electronic components (i.e. hardware) and any software and/orfirmware (“code”) which may configure the hardware, be executed by thehardware, and or otherwise be associated with the hardware. As usedherein, for example, a particular processor and memory may comprisefirst “circuitry” when executing a first one or more lines of code andmay comprise second “circuitry” when executing a second one or morelines of code. As utilized herein, “and/or” means any one or more of theitems in the list joined by “and/or”. As an example, “x and/or y” meansany element of the three-element set {(x), (y), (x, y)}. In other words,“x and/or y” means “one or both of x and y”. As another example, “x, y,and/or z” means any element of the seven-element set {(x), (y), (z), (x,y), (x, z), (y, z), (x, y, z)}. In other words, “x, y and/or z” means“one or more of x, y and z”. As utilized herein, the term “exemplary”means serving as a non-limiting example, instance, or illustration. Asutilized herein, the terms “e.g.,” and “for example” set off lists ofone or more non-limiting examples, instances, or illustrations. Asutilized herein, circuitry is “operable” to perform a function wheneverthe circuitry comprises the necessary hardware and code (if any isnecessary) to perform the function, regardless of whether performance ofthe function is disabled or not enabled (e.g., by a user-configurablesetting, factory trim, etc.).

What is claimed is:
 1. A system comprising: a computing devicecomprising a frontend and a backend, wherein the frontend is a virtualfrontend filesystem that is configured to encrypt data as it enters thesystem, and wherein the backend is a virtual backend filesystem thatcomprises a plurality of buckets; and a plurality of storage devices,wherein: each bucket of the plurality of buckets is configured to builda failure-protected stripe that comprises a plurality of failureresilient address spaces across a plurality of storage blocks, eachstorage block of a failure-protected stripe is located in a differentstorage device of the plurality of storage devices, the encrypted datais stored in a file in one or more failure-protected stripes, thecomputing device is in a cluster of computing devices, the cluster ofcomputing devices is associated with a cluster key, the computing deviceregisters a long-term key with a leader of the cluster when thecomputing device joins the cluster of computing devices, and prior to atransfer of the data, a session key is negotiated using an ephemeral keypair signed with the long-term key.
 2. The system of claim 1, whereinthe frontend is operable to decrypt data as it leaves the system.
 3. Thesystem of claim 1, wherein the frontend encrypts the data according to afile key.
 4. The system of claim 3, wherein the file key is rotated whenthe file is copied.
 5. The system of claim 3, wherein allfailure-protected stripes built by the plurality of buckets in thebackend are associated with a filesystem key.
 6. The system of claim 5,wherein the file key is encrypted by the filesystem key.
 7. The systemof claim 5, wherein the file key is re-encrypted when the filesystem keyis rotated.
 8. A method comprising: opening a data file for a writeaccess to a filesystem on a computing device, wherein: the computingdevice comprises a frontend, a backend and a plurality of storagedevices, the frontend is a virtual frontend filesystem, the backend is avirtual backend filesystem that comprises a plurality of buckets, eachbucket of the plurality of buckets is configured to build afailure-protected stripe that comprises a plurality of failure resilientaddress spaces across a plurality of storage blocks, each storage blockof the plurality of storage blocks in a failure-protected stripe islocated in a different storage device of the plurality of storagedevices, the computing device is in a cluster of computing devices, andthe cluster of computing devices is associated with a cluster key;registering a long-term key, of the computing device, with a leader ofthe cluster when the computing device joins the cluster of computingdevices, negotiating a session key using an ephemeral key pair signedwith the long-term key; encrypting data in the frontend using thesession key; transferring the data encrypted by the session key to thecomputing device; writing the encrypted data to the data file in one ormore failure-protected stripes built by one or more buckets of theplurality of buckets; and closing the data file.
 9. The method of claim8, wherein the frontend is operable to decrypt data as it is read. 10.The method of claim 8, wherein the frontend encrypts the data accordingto a file key; and the method comprises purging the file key from memoryafter the data file is closed.
 11. The method of claim 10, wherein themethod comprises rotating the file key by copying the data file.
 12. Themethod of claim 10, wherein all failure-protected stripes built by theplurality of buckets in the backend are associated with a filesystemkey.
 13. The method of claim 12, wherein the file key is encrypted bythe filesystem key.
 14. The method of claim 12, wherein the methodcomprises re-encrypting the file key when the filesystem key is rotated.